THE ROLE OF THE SURFACE IN TRANSIENT ENHANCED DIFFUSION

The enhanced diffusion of impurities that is seen following ion implantation is rapidly quenched, hence, the name transient enhanced diffusion (TED). The quenching of TED is associated with the annealing of implant damage, either by the diffusion of point defects to the bulk or to the surface. It is variously assumed that either the surface or the bulk is the predominant annealing site. In this work, we explore these assumptions by observing the reduction of TED in a buried marker, when the surface is etched to bring it closer to implanted damage. The results show a considerable reduction in TED with surface etching, demonstrating that the surface plays a key role in annealing implant damage. Numerical modeling allows extraction of the surface recombination length of interstitials at 800 degrees C. Only a value of 0.1 mu m is consistent with the data. All but a very small fraction of implanted interstitials are recombined at the surface with this value. (C) 1995 American Institute of Physics.